1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method suitable for processing a substrate with a plurality of liquids.
2. Description of the Related Art
As an interconnection forming process of a semiconductor device, there has been used a process of embedding a metal (conductive material) in interconnection grooves and contact holes (so-called damascene process). This process comprises embedding a metal such as aluminum, or, recently, copper or silver, in interconnection grooves and contact holes, which have been formed in an interlayer insulating film, and then removing and planarizing excessive metal by chemical mechanical polishing (CMP).
In cases of these types of interconnections, for example, copper interconnections using copper as an interconnection material, surfaces of the interconnections made of copper are exposed to the outside after the planarization process. In order to prevent thermal diffusion of interconnections (copper), or in order to prevent oxidation of interconnections (copper), for example, when a semiconductor device having a multilayer interconnection structure is subsequently formed by laminating insulating films (oxide films) under an oxidizing atmosphere, there has been considered to selectively cover the exposed surfaces of the interconnections with interconnection protective layers (covering material) made of Co alloy, Ni alloy, or the like. Co alloy, Ni alloy, or the like can be obtained by, for example, electroless plating.
Here, for example, a case as shown in FIG. 10 is assumed. Specifically, a fine recess 212 for an interconnection is formed within an insulating film 210 such as SiO2 deposited on a surface of a substrate W such as a semiconductor wafer, a barrier layer 214 such as TaN is formed on surfaces of the insulating film, then, for example, copper plating is performed to deposit a copper film on the surface of the substrate W to embed the recess 212 with the copper film, thereafter, CMP (chemical mechanical polishing) for planarization is performed on the surface of the substrate W to thus form an interconnection 216 of the copper film in the insulating film 210, and an interconnection protective layer (covering material) 218 of a Co—W—P alloy film is selectively formed on a surface of the interconnection (copper film) 216 to protect the interconnection 216.
There will be described a process of selectively forming such an interconnection protective layer (covering material) 218 of a Co—W—P alloy film on a surface of an interconnection 216 by general electroless plating. First, a substrate W such as a semiconductor wafer which has been subject to a CMP process is immersed in an acidic solution such as H2SO4 of 0.5 M which has a temperature of, for example, 25° C. for about 1 minute to thus remove a CMP residue or the like, such as copper remaining on the surface of the insulating film 210. Then, after the surface of the substrate W is cleaned with a cleaning liquid such as ultra pure water, the substrate W is immersed in a mixture solution such as a mixture of PdCl2 of 0.005 g/L and HCL of 0.2 ml/L which has a temperature of, for example, 25° C. for about 1 minute to thus attach Pd as a catalyst onto the surface of the interconnection 216 to activate an exposed surface of the interconnection 216. Next, after the surface of the substrate W is cleaned with a cleaning liquid such as ultra pure water, the substrate W is immersed in a solution of Na3C6H5O7.2H2O (sodium citrate) of 20 g/L which has a temperature of, for example, 25° C. to thus neutralize the surface of the interconnection 216. Then, after the surface of the substrate W is rinsed with ultra pure water, the substrate W is immersed in a Co—W—P plating solution having a temperature of, for example, 80° C. for about 120 seconds to thus perform electroless plating (electroless Co—W—P cover plating) selectively on the activated surface of the interconnection 216, and then the surface of the substrate W is cleaned with a cleaning liquid such as ultra pure water. Thus, an interconnection protective layer 218 of a Co—W—P alloy film is selectively formed on the surface of the interconnection 216 to protect the interconnection 216.
Incidentally, among the above processes, a process of cleaning the substrate W with a cleaning liquid after immersing the substrate in an acidic solution such as H2SO4, a process of cleaning the substrate W with a cleaning liquid after immersing the substrate in a mixture solution such as a mixture of PdCl2 and HCL, and a process of cleaning the substrate W with a cleaning liquid after immersing the substrate in the solution such as sodium citrate have been performed with a pretreatment unit 240, as shown in FIG. 11, comprising a chemical liquid chamber 250, a cleaning chamber (rinsing chamber) 255, a substrate holding device (substrate holding means) 261 for holding a substrate on a lower surface thereof, and an arm 265 for swingably supporting the substrate holding device 261. The substrate holding device, which has held a substrate on the lower surface thereof, is moved right above the chemical liquid chamber 250 and lowered to attach a chemical liquid onto a lower surface of the substrate, and a chemical liquid treatment is performed while the substrate holding device is being rotated. Next, after the substrate is lifted right above the chemical liquid chamber 250, the arm 265 is swung to move the substrate holding device 261 right above the cleaning chamber 255 and lowered, and the chemical liquid attached onto the lower surface of the substrate is cleaned while the substrate is being rotated and a cleaning liquid is being ejected. Next, after the substrate is lifted right above the cleaning chamber 255, the arm 265 is swung to deliver the substrate to the next process.
However, in the above conventional pretreatment unit 240, since it is necessary to provide two treatment chambers for a chemical liquid treatment and for a cleaning process, not only does an area for installing the apparatus increase so as to occupy a large space, but also the cost of the apparatus increases because a swinging mechanism for the arm 265 is required. These problems are also applicable to a plating unit having a plating chamber and a cleaning chamber.